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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TASK_RUNNER_UTIL_H_
#define BASE_TASK_RUNNER_UTIL_H_
#pragma once
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/logging.h"
#include "base/task_runner.h"
namespace base {
namespace internal {
// Helper class for TaskRunner::PostTaskAndReplyWithResult.
template <typename ReturnType>
void ReturnAsParamAdapter(const Callback<ReturnType(void)>& func,
ReturnType* result) {
if (!func.is_null())
*result = func.Run();
}
// Helper class for TaskRunner::PostTaskAndReplyWithResult.
template <typename ReturnType>
Closure ReturnAsParam(const Callback<ReturnType(void)>& func,
ReturnType* result) {
DCHECK(result);
return Bind(&ReturnAsParamAdapter<ReturnType>, func, result);
}
// Helper class for TaskRunner::PostTaskAndReplyWithResult.
template <typename ReturnType>
void ReplyAdapter(const Callback<void(ReturnType)>& callback,
ReturnType* result) {
DCHECK(result);
if(!callback.is_null())
callback.Run(*result);
}
// Helper class for TaskRunner::PostTaskAndReplyWithResult.
template <typename ReturnType, typename OwnedType>
Closure ReplyHelper(const Callback<void(ReturnType)>& callback,
OwnedType result) {
return Bind(&ReplyAdapter<ReturnType>, callback, result);
}
} // namespace internal
// When you have these methods
//
// R DoWorkAndReturn();
// void Callback(const R& result);
//
// and want to call them in a PostTaskAndReply kind of fashion where the
// result of DoWorkAndReturn is passed to the Callback, you can use
// PostTaskAndReplyWithResult as in this example:
//
// PostTaskAndReplyWithResult(
// target_thread_.message_loop_proxy(),
// FROM_HERE,
// Bind(&DoWorkAndReturn),
// Bind(&Callback));
template <typename ReturnType>
bool PostTaskAndReplyWithResult(
TaskRunner* task_runner,
const tracked_objects::Location& from_here,
const Callback<ReturnType(void)>& task,
const Callback<void(ReturnType)>& reply) {
ReturnType* result = new ReturnType;
return task_runner->PostTaskAndReply(
from_here,
internal::ReturnAsParam<ReturnType>(task, result),
internal::ReplyHelper(reply, Owned(result)));
}
} // namespace base
#endif // BASE_TASK_RUNNER_UTIL_H_
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